If it makes you feel any better, mine at that age pulled the top down and poked at each nipple. Right in the middle of class. With all the other parents watching. I was horrified. I'd never seen her show any interest in those before so why then? In public? I've never seen her do it again since, not that I'm alway watching. To protect the innocent, I'm not going to point out which of my little darlings did this. :-)